Gallium Scan

Test Overview

A gallium scan is a
nuclear medicine test. A nuclear medicine test uses a
special camera to take pictures of specific tissues in the body after a
radioactive tracer (radionuclide or radioisotope) makes them visible. Each type
of tissue that may be scanned (including bones, organs, glands, and blood
vessels) uses a different radioactive compound as a tracer. The radioactivity
of a tracer decreases over a period of hours, days, or weeks. The tracer stays
in the body until it is eliminated as waste, usually in the urine or stool
(feces).

During a gallium scan, the tracer (radioactive gallium
citrate) is injected into a vein in the arm. It travels through the bloodstream
and into the body's tissues, primarily the bones, liver, intestine, and areas
of tissue where inflammation or a buildup of
white blood cells (WBCs) is present. It often takes
the tracer a few days to build up in these areas, so in most cases a scan is
done at 2 days and again at 3 days after the tracer is injected. Areas where
the tracer builds up in higher-than-normal amounts show up as bright or "hot"
spots in the pictures. The problem areas may be caused by infection, certain
inflammatory diseases, or a tumor.

Why It Is Done

A gallium scan is done to:

Detect the source of an infection that is
causing a fever (called a fever of unknown origin).

Detect certain types of
cancer (such as
lymphoma). A gallium scan also may be done to see if
cancer has spread (metastasized) to other areas of the body, or to watch how
well a cancer treatment is working.

How To Prepare

Before the gallium scan, tell your
doctor if:

You are or might be pregnant.

You
are breast-feeding. If you will no longer be breast-feeding after the test, you
will be asked to stop breast-feeding 2 weeks before the test so that the
radioactive tracer will not build up in your breast tissue. If you will
continue to breast-feed after the test, it is recommended that you not use your
breast milk for 4 weeks after a gallium scan because the tracer can be passed
to your baby. Some doctors may advise you to stop breast-feeding completely
after this scan.

Within the 4 days before the gallium scan, you
have had an X-ray test using barium
contrast material (such as a
barium enema) or have taken a medicine (such as
Pepto-Bismol) that contains bismuth. Barium and bismuth can interfere with test
results.

Gallium builds up in the large intestine (colon) before it
is eliminated in the stool. You may need to take a laxative the night before
the scan and have an enema 1 to 2 hours before the scan to prevent the gallium
in your colon from interfering with pictures of the area being studied.

Talk to your doctor about any concerns you have regarding the need for
the test, its risks, how it will be done, or what the results will mean. To
help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).

How It Is Done

The
technologist cleans the site on your arm where the radioactive tracer will be
injected. A small amount of the radioactive tracer is then injected. You will
need to return for the diagnostic scans. Gallium
scans are usually done 24 hours (1 day), 48 hours (2 days), and 72 hours (3 days)
after the tracer is injected.

When you come in for the scan, you
will need to remove any jewelry that might interfere with the scan. You may
need to take off all or most of your clothes, depending on which area is being
examined (you may be allowed to keep on your underwear if it does not interfere
with the test). You will be given a cloth or paper covering to use during the
test.

You will lie on your back on a table, and a large scanning
camera will be positioned closely above you. After the radioactive tracer is
injected, the camera will scan for radiation released by the tracer and produce
pictures of the tracer in your tissues. The camera may move slowly above and
around your body. The camera does not produce any radiation, so you are not
exposed to any additional radiation while the scan is being done.

You may be asked to move into different positions so the area of interest
can be viewed from other angles. You need to lie very still during each scan to
avoid blurring the pictures. You may be asked to hold your breath briefly
during some of the scans.

Each scan may take about 60 to 90
minutes.

How It Feels

You may feel nothing at all from the
needle puncture when the tracer is injected, or you may feel a brief sting or
pinch as the needle goes through the skin. Otherwise, a gallium scan is usually
painless. You may find it difficult to remain still during the scan. Ask for a
pillow or blanket to make yourself as comfortable as possible before the scan
begins.

Risks

There is always a slight risk of damage to
cells or tissue from being exposed to any radiation, including the low level of
radiation released by the radioactive tracer used for this test.

Allergic reactions to the radioactive tracer are rare.
Most of the tracer will be eliminated from your body (through your urine or
stool) within 4 days. The amount of radiation is so small that it is not a risk
for people to come in contact with you following the test.

Sometimes you may have soreness or swelling at the injection site. These
symptoms can usually be relieved by applying moist, warm compresses to your
arm.

Results

A gallium scan is a
nuclear medicine test that uses a special camera to
take pictures of certain tissues in the body after a radioactive tracer
(radionuclide or radioisotope) makes them visible. The results of a gallium
scan are usually available within 2 days after the scans are completed.

Gallium scan

Normal:

The collection and activity of gallium in
the bones, liver, spleen, and large intestine (colon) is normal. No areas of
unusual gallium accumulation are seen.

Abnormal:

An abnormally high gallium accumulation
(hot spot) is present in one or more areas of the body, possibly meaning
inflammation, infection, or a tumor.

What Affects the Test

Reasons you may not be able to
have the test or why the results may not be helpful include:

Pregnancy. A gallium scan is not usually done
during pregnancy because the radiation could damage the developing baby (fetus).

Having barium or bismuth in your
system. If a gallium scan is needed, it should be done before any tests that
use barium (such as a
barium enema). Taking a medicine (such as
Pepto-Bismol) that contains bismuth can also interfere with a gallium
scan.

Not being able to remain still during the test.

What To Think About

A gallium scan is used for specific types of
cancers, mainly of the
lymph nodes, bones, or
bone marrow. A normal scan does not exclude the
possibility of cancer, because some types of cancer do not show up on a gallium
scan. A gallium scan also cannot determine whether a tumor is cancerous
(malignant) or noncancerous (benign).

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